With Nvidia's GeForce3 graphics processor card set to arrive by April, Mac users are looking forward to a future of faster frame rates and more vivid, realistic games. But if you're wondering what immediate impact the brand new graphics card will have on your Mac, you may want to consider the debut of another processor that featured a breakthrough technology.

A little more than a year ago, the first G4 Macs were introduced, along with the AltiVec subprocessor. AltiVec processes data with an expanded instruction set, enabling the G4 processor to work on several portions of data at once. Basically, AltiVec allows a G4 to render graphics, encode sound, and perform calculations faster than a G3 chip with the same listed processor speed could.

To take advantage of AltiVec, though, developers have to modify their applications. And while some key programs have been retooled -- including Adobe Photoshop, Macromedia Director, and Connectix Virtual PC -- there hasn't been a rush by developers to modify their software. The reason? Many developers believe the size of the Mac market doesn't justify the expense of modifying applications to benefit from AltiVec.

And therein lies the dilemma facing GeForce3.

Graphically Better

Few would dispute the argument that
Nvidia
has built a better graphics chip. Since it was unveiled at last month's Macworld Expo Tokyo, the GeForce3 has been hailed as the greatest graphics card on any platform ever -- a quantum leap forward in graphics processing units.

Just as the G4's extra kick comes from AltiVec, the GeForce3 relies on a proprietary chip technology called the NfiniteFX engine. NfiniteFX allows programmers to create rich, 3-D worlds with personalized combinations of graphics options.

Two features power NfiniteFX -- Vertex Shaders and Pixel Shaders. Vertex Shaders helps programmers build detailed motion into all aspects of a game rather than just the central focal points. That helps the entire screen come alive. Pixel Shaders allows programmers to create rich textures and surfaces that mimic reality, giving games a look that's closer to the real world.

Not insignificantly, the GeForce3 also happens to be fast. It's twice the speed of most graphics cards on the market today.

The AltiVec Conundrum

But to get all this performance out of the GeForce3, game developers have to write specifically for the processor. And that has some Mac gamers worried that the same problems keeping AltiVec from gaining wider acceptance will affect the GeForce3 as well.

Macs make up less than 10 percent of the PC market -- the number of Mac users with GeForce3 cards will likely make up an even smaller percentage. How, then, do Mac gaming developers justify the added expense of producing GeForce3-enhanced games?

"We don't have any developers that are working on games for Mac GeForce 3," says Michael Larson, senior publicist with
Activision.

Wintel to the Rescue?

But don't write off the GeForce3 just yet. Enhanced games that take advantage of the graphics chip will come to the Mac, but from an unlikely source -- PCs.

Developers will likely produce games for the GeForce3 on the PC side and then port them over to the Mac. That doesn't require the resources that writing games specifically for the Mac would require.

"Porting PC games that take advantage of the GeForce3 shouldn't be more difficult than any other port," says John Stiles, a Mac-gaming developer at
Blizzard Entertainment. "Nvidia has written a handful of OpenGL extensions which allow developers to access the new proprietary GeForce3 feature set. Fortunately, these OpenGL extensions are supported equally on the Mac and the PC. This makes for a phenomenally simple port. In many cases, these OpenGL extensions could work on the Mac with no extra development effort at all."

That's a contrast to the AltiVec situation. "With AltiVec it really depended on what you were doing as to whether you would see any real performance gains," says Michael Rogers, CEO of
Aspyr. "You might get a couple of percentage points and that wasn't enough to justify it. Because there's such a noticeable difference you're going to see [the GeForce3] more widely supported."

Aspyr, one of the largest publishers of games for the Mac, plans on updating its titles, and expects to see other companies do the same when the GeForce3 ships.

"It depends on what the original developer does," Rogers says. "We haven't seen too much of the driver stuff yet, but I feel like people are going to jump on it pretty quickly."

Blizzard's Stiles agrees. "I suppose [coding for the card] really depends on the rate of adoption for a $600 video card in the gaming market," he says. "Until a significant percentage of the market owns a GeForce3-equivalent card, you probably won't see too many games that depend on the NfiniteFX feature set. But that doesn't mean you shouldn't get a GeForce. It will still provide the best highest level of 3-D performance ever seen on any platform."

And Nvidia isn't giving up hope of getting Mac software developers to support the GeForce3 in native applications. The company is working closely with Apple's Developer Tech Support engineers to create a software development kit that will enable Mac apps to be optimized for the GeForce3 hardware.